Disclosed herein are amide gellant compounds with aromatic end groups and ink compositions containing the compounds. One embodiment disclosed herein is directed to a phase change ink comprising a colorant, an initiator, and a phase change ink carrier comprising at least one radically curable monomer compound and a compound of the formula

wherein R1 and R1′ are the same, and wherein R1 and R1′ each are aromatic groups; wherein R2 and R2′ are the same or different, and wherein R2 and R2′ are each independently selected from (i) alkylene groups, which can be linear or branched, saturated or unsaturated, cyclic or acyclic, substituted or unsubstituted alkylene groups, and wherein hetero atoms may optionally be present in the alkylene group; (ii) arylene groups, which can be substituted or unsubstituted arylene groups, and wherein hetero atoms may optionally be present in the arylene group; (iii) arylalkylene groups, which can be substituted or unsubstituted arylalkylene groups, wherein the alkyl portion of the arylalkylene group can be linear or branched, saturated or unsaturated, cyclic or acyclic, and substituted or unsubstituted, and wherein hetero atoms may optionally be present in either the aryl portion or the alkyl portion of the arylalkylene group; or (iv) alkylarylene groups, which can be substituted or unsubstituted alkylarylene groups, wherein the alkyl portion of the alkylarylene group can be linear or branched, saturated or unsaturated, cyclic or acyclic, and substituted or unsubstituted, and wherein hetero atoms may optionally be present in either the aryl portion or the alkyl portion of the alkylarylene group; and wherein R3 is (i) a linear or branched alkylene group, which can be saturated or unsaturated, and substituted or unsubstituted alkylene groups, and wherein hetero atoms may optionally be present in the alkylene group; (ii) an arylene group, which can be substituted or unsubstituted arylene groups, and wherein hetero atoms may optionally be present in the arylene group; (iii) an arylalkylene group, which can be substituted or unsubstituted arylalkylene groups, wherein the alkyl portion of the arylalkylene group can be linear or branched, saturated or unsaturated, cyclic or acyclic, and substituted or unsubstituted, and wherein hetero atoms may optionally be present in either the aryl portion or the alkyl portion of the arylalkylene group; or (iv) an alkylarylene group, which can be substituted or unsubstituted alkylarylene groups, wherein the alkyl portion of the alkylarylene group can be linear or branched, saturated or unsaturated, cyclic or acyclic, and substituted or unsubstituted, and where hetero atoms may optionally be present in either the aryl portion or the alkyl portion of the alkylarylene group.
In general, phase change inks (sometimes referred to as “hot melt inks”) are in the solid phase at ambient temperature, but exist in the liquid phase at the elevated operating temperature of an ink jet printing device. At the jet operating temperature, droplets of liquid ink are ejected from the printing device and, when the ink droplets contact the surface of the recording substrate, either directly or via an intermediate heated transfer belt or drum, they quickly solidify to form a predetermined pattern of solidified ink drops. Phase change inks have also been used in other printing technologies, such as gravure printing.
Phase change inks for color printing typically comprise a phase change ink carrier composition which is combined with a phase change ink compatible colorant. A series of colored phase change inks can be formed by combining ink carrier compositions with compatible subtractive primary colorants. The subtractive primary colored phase change inks can comprise four component dyes, namely, cyan, magenta, yellow and black, although the inks are not limited to these four colors. These subtractive primary colored inks can be formed by using a single dye or a mixture of dyes. For example, magenta can be obtained by using a mixture of Solvent Red Dyes or a composite black can be obtained by mixing several dyes. U.S. Pat. Nos. 4,889,560, 4,889,761, and 5,372,852, the disclosures of each of which are totally incorporated herein by reference, teach that the subtractive primary colorants employed can comprise dyes from the classes of Color Index (C.I.) Solvent Dyes, Disperse Dyes, modified Acid and Direct Dyes, and Basic Dyes. The colorants can also include pigments, as disclosed in, for example, U.S. Pat. No. 5,221,335, the disclosure of which is totally incorporated herein by reference. U.S. Pat. No. 5,621,022, the disclosure of which is totally incorporated herein by reference, discloses the use of a specific class of polymeric dyes in phase change ink compositions.
Phase change inks have also been used for applications such as postal marking, industrial marking, and labeling.
Phase change inks are desirable for ink jet printers because they remain in a solid phase at room temperature during shipping, long term storage, and the like. In addition, the problems associated with nozzle clogging as a result of ink evaporation with liquid ink jet inks are largely eliminated, thereby improving the reliability of the ink jet printing. Further, in phase change ink jet printers wherein the ink droplets are applied directly onto the final recording substrate (for example, paper, transparency material, and the like), the droplets solidify immediately upon contact with the substrate, so that migration of ink along the printing medium is prevented and dot quality is improved.
Compositions suitable for use as phase change ink carrier compositions are known. Suitable carrier materials can include paraffins, microcrystalline waxes, polyethylene waxes, ester waxes, fatty acids and other waxy materials, fatty amide containing materials, sulfonamide materials, resinous materials made from different natural sources (tall oil rosins and rosin esters, for example), and many synthetic resins, oligomers, polymers, and copolymers.
U.S. Pat. No. 7,276,614 (Eniko Toma, et al.), which is hereby incorporated by reference herein in its entirety, discloses curable ester-terminated oligoamide compounds and ink compositions containing them. Disclosed are compounds of the formula

wherein R1 and R1′ each, independently of the other, is an alkyl group having at least one ethylenic unsaturation, an arylalkyl group having at least one ethylenic unsaturation, or an alkylaryl group having at least one ethylenic unsaturation, R2, R2′, and R3 each, independently of the others, are alkylene groups, arylene groups, arylalkylene groups, or alkylarylene groups, and n is an integer representing the number of repeat amide units and is at least 1.
U.S. Pat. No. 7,279,587 (Peter G. Odell, et al.), which is hereby incorporated by reference herein in its entirety, discloses photoinitiating compounds compatible with or useful in phase change ink compositions. Disclosed are compounds of the formula

wherein R1 is an alkylene, arylene, arylalkylene, or alkylarylene group, R2 and R2′ each, independently of the other, are alkylene, arylene, arylalkylene, or alkylarylene groups, R3 and R3′ each, independently of the other, are either (a) photoinitiating groups, or (b) groups which are alkyl, aryl, arylalkyl, or alkylaryl groups, provided that at least one of R3 and R3′ is a photoinitiating groups, and X and X′ each, independently of the other, is an oxygen atom or a group of the formula —NR4—, wherein R4 is a hydrogen atom, and alkyl group, an aryl group, or an alkylaryl group.
U.S. Pat. No. 5,783,657 (Mark S. Pavlin, et al.), which is hereby incorporated by reference herein in its entirety, discloses low molecular weight, ester-terminated polyamides which may be blended with a liquid hydrocarbon to form a transparent composition having gel consistency. The ester-terminated polyamide is prepared by reacting “x” equivalents of dicarboxylic acid wherein at least 40% of those equivalents are from polymerized fatty acid, “y” equivalents of diamine such s ethylene diamine, and “z” equivalents of monoalcohol having at least 4 carbon atoms. The stoichiometry of the reaction mixture is such that 0.9≦{x/(y+z)}≦1.1 and 0.1≦{z/(y+z)}≦0.7. The reactants are heated until they reach reaction equilibrium. The gel contains about 5-50% ester-terminated polyamide, with the remainder preferably being pure hydrocarbon. The gels are useful in formulating personal care products and other articles wherein some degree of gel-like or self-supporting consistency is desired.
U.S. Pat. No. 6,111,055 (Vivian Berger, et al.), which is hereby incorporated by reference herein in its entirety, discloses an ester-terminated dimer acid-based polyamide may be blended with a solvent to form a gel. The solvent may be flammable, and a wick may be added to the resulting gel so as to form a candle.
While known compositions and processes are suitable for their intended purposes, a need remains for improved phase change ink compositions. In addition, a need remains for phase change inks that produce images with improved scratch resistance. Further, a need remains for phase change inks that produce images with improved adhesion to substrates such as paper. There is also a need for ultraviolet curable compounds that can be incorporated into phase change ink carriers without adversely affecting the viscosity characteristics of the ink at desired jetting temperatures. In addition, there is a need for ultraviolet curable compounds that can be incorporated into phase change ink carriers without adversely affecting the melting point of the ink. Additionally, there is a need for ultraviolet curable phase change inks that can be used in ink jet printing processes wherein the ink is jetted directly onto a final substrate such as paper or transparency material. A need also remains for phase change inks that generate images that exhibit improved robustness on the final recording sheet. In addition, a need remains for phase change inks that generate images with improved toughness. Further, a need remains for phase change inks that can be jetted at reduced temperatures. Additionally, a need remains for phase change inks that enable control of dot spread of the ink, particularly in processes wherein the ink is jetted directly onto a final substrate. In addition, there is a need for phase change inks wherein the ink does not bleed excessively into the substrate, particularly in processes wherein the ink is jetted directly onto a final substrate. Further, there is a need for phase change inks wherein the ink does not generate an undesirably high pile height and wherein an unnecessarily high number of drops are needed to create the image, particularly in processes wherein the ink is jetted directly onto a final substrate. Additionally, there is a need for phase change inks wherein the ink generates images with reduced showthrough. A need also remains for phase change inks wherein the increased viscosity of the ink during photoinitiation reduces the rate of diffusion of oxygen and its inhibitory effect in the ink, thereby increasing the efficiency of cure. In addition, a need remains for improved ultraviolet curable phase change ink compositions used in, for example, but not limited to, production printing. Further, there remains a need for an improved phase change ink composition providing wide substrate latitude, excellent adhesion, and enhanced pigment dispersion stability. Further, a need remains for gellant compositions for phase change inks that can provide enhanced spectral transmission and gelation properties. Further, there remains a need for a gellant composition for phase change inks that can be readily produced and that does not require post reaction purification to achieve the desired gellant composition. Further, there remains a need for a gellant that can provide adequate gelation strength without the need for complex processing steps. Further, there remains a need for a gellant that has high thermal stability.
The appropriate components and process aspects of the each of the foregoing U.S. Patents and Patent Publications may be selected for the present disclosure in embodiments thereof. Further, throughout this application, various publications, patents, and published patent applications are referred to by an identifying citation. The disclosures of the publications, patents, and published patent applications referenced in this application are hereby incorporated by reference into the present disclosure to more fully describe the state of the art to which this invention pertains.